Levels of intact HTT (i.e., full-length HTT) were greatly reduced in the STR of HD cases (as early as HD2) compared to controls when detected by an N-terminal antibody, mEM48 (13) (Fig. 3A, fl (full-length)*; Fig. 3C, left), while the difference in the levels of this HTT species in the CTX between the control and HD cases was only marginal (Fig. 3B, fl*; Fig. 3C, left). Here, HTT is linked to Huntington disease.